In 3rd Generation Partnership Project (3GPP) which is a mobile communication system standardization project, a technique of selecting a target cell to be used as a serving cell from among a plurality of cells operated at different frequencies has been proposed.
Specifically, in a case in which a start condition is satisfied, a user terminal measures qualities of neighbor cells adjacent to a current serving cell and selects a target cell to be used as a serving cell from among cells satisfying a selection condition.